The overall goal of this work is to produce a wearable continuous alcohol monitor that is pain- free and noninvasive, with wireless communications capability to enable remote monitoring. The monitor centers around a novel biosensor consisting of a multi-well flexible microchip that disrupts the outer layer of dead skin cells, the stratum corneum (SC), to access interstitial fluid (ISF). Current versions of the chip are in development to monitor glucose for patients with diabetes and these versions were used to prove the core technology. The device was shown to sample ISF painlessly from the arm of human subjects, and to detect glucose with high sensitivity and specificity in vitro. The device is currently being prepared for a human study at the Walter Reed Army Diabetes Center. In this study we will adapt the glucose sensor to measure alcohol. The electrochemical detection strategy utilizes alcohol oxidase which is very similar to the technology used on the glucose sensor (which was based on glucose oxidase). We will rely on our expertise in producing sensors to ensure the alcohol monitor detects alcohol in the body reliably. Moreover, a strength of the technology platform is that it can support additional chemistries to monitor other substances that may be present in the ISF, including drugs in addition to alcohol. The scope of the work proposed herein is to adapt the existing glucose sensor for alcohol monitoring and test its function in vitro. The specific aims of this project are: 1. Finalize alcohol detection chemistry. The alcohol detection layer will initially be created using the same strategy and chemicals as the glucose monitor. The detection approach will first be verified by coating on a macro electrode and characterizing the response to alcohol. Changes in the detection chemistry, if needed, will be made on the macro electrode. 2. Functionalize FMS chip. The existing chip platform will be functionalized to detect alcohol. The detection chemistry that gave the best results on the macro electrode will be applied to the FMS chip, and the approach verified in alcohol solutions. 3. Characterize alcohol sensor. The sensitivity, specificity, response time, and measurement life will be determined in in vitro tests. PUBLIC HEALTH RELEVANCE Several features of the FMS device represent significant advances for alcohol monitoring over the SCRAM and other alcohol monitors: 7 The sampling process is painless and automatic, which will dramatically increase compliance. 7 The detection component uses chemistries similar to those already in use that provide accurate glucose measurement in ISF. 7 The device allows frequent, near-continuous monitoring of alcohol levels which is important for trending, which can bolster the validity of measurements. 7 The slim profile of a wearable patch enables discreet monitoring. 7 Flexible printed circuits may be manufactured inexpensively with dozens of sample wells on each chip. This extends wear length and lowers end user costs. 7 The sampling process is minimally-invasive (nothing inserts into the skin), only applies heat and electricity periodically, and relies on passive diffusion. There will be fewer long- term complications such as irritation and bruising that have resulted from wearing SCRAM monitors. 7 The ISF sampling approach should provide a more direct measure of BAC with less of a time lag than transdermal alcohol monitoring. 7 The FMS device offers a platform for other potential applications that could benefit from easier monitoring, including sobriety tests for social drinkers;alcohol monitoring for pilots, teachers, and other employees;and testing for other substances.